About the Milvon to West River Transmission Line Rebuild Project
Learn more about the project.Read More
Learn more about the project.Read More
The UI Railroad Transmission Line Upgrade Project rebuilds UI’s transmission lines along the 25 miles of the Metro North Railroad(MNR) corridor between Fairfield and West Haven. This includes installation of approximately 500 new foundation supported galvanized transmission poles, upgrading of conductor size and installing sectionalizing switches at nearby substations. This project will enhance the structural integrity and reliability of the high voltage transmission lines along the MNR corridor allowing UI to continue to provide safe, reliable electric service to our customers for years to come.
The upgrades will improve the reliability and resiliency of the transmission system, ensuring that the safe and reliable transmission of power is maintained throughout Fairfield and New Haven County in accordance with Federal reliability standards.
Construction start of first phase: Dec. 2017
Estimated in-service date of final phase: 2028 Q3
Phase 1 - Baird Substation to Congress Substation
115kV Transmission Line Upgrade
Phase 2 - Housatonic River
Stratford 115-kV Transmission Line Upgrade Project consisting of the removal and relocation of northern and southern sections of existing 115-kilovolt (kV) transmission line structures from Connecticut Department of Transportation (ConnDOT) catenary structures within the Metro-North Railroad corridor to new 115-kV transmission line structures to be located within the existing ConnDOT right of way and upgrade of 115-kV conductors extending approximately 1.9 miles from UI’s Baird Substation to just west of the Housatonic River in Stratford, Connecticut, and related substation improvements
Rebuild 9.5 miles from Milvon Substation (Milford, CT) to West River Substation (New Haven, CT).
Relocate the transmission lines off the existing CT DOT railroad catenary bonnets and install on independent monopoles with new insulators, hardware and conductor on new monopole structures in the railroad corridor.
Additional Links and Documents
UI is committed to working cooperatively with our customers, neighbors, community leaders and regulators as we improve reliability while minimizing disruption to the environment and community. We have a dedicated team of public outreach liaisons who will be involved throughout the duration of the project to answer any questions you may have.
Below are the stages of the project construction process that you may see in your community.
1) Laying matting and building access roads for construction vehicles while protecting the area
2) Tree clearing – trimming "danger trees" that may cause service interruption
3) Drilling foundations which will support the new galvanized steel poles
4) Setting the bolt cage for the foundation structure
5) Pouring concrete for the foundations
6) Final concrete cap for the steel monopoles
7) Setting the poles into the foundation
8) Stringing the wire (conductor) onto the poles
9) Restoration - grading, seeding & mulch. Access roads removed.
Updated May 2020
UI is designing the Project to avoid and minimize negative impacts to the community and the environment. Early Project planning efforts included the completion of a set of resource assessments to clarify important planning considerations such as water resources; soil characteristics; cultural resources; and sensitive plant and animal species. Active regulatory coordination and reviews preceded numerous permitting efforts and are ongoing through the construction phase of the Project. UI has secured the necessary authorizations reviews and permits from agencies across federal, state and local administration agencies. Consultations and permits have been pursued from the following agencies for the Project:
State of Connecticut
Local and Regional
|CT DEEP Natural Diversity Database Species Protection Best Management Practices||12/23/2021|
|Typical Structure Foundation Details||12/23/2021|
|Connecticut Siting Council Process||12/23/2021|
|FAQ Sheet - Milvon to West River||12/20/2021|
|Visual Simulations as shown in the Municipal Consultation filing on 11/28/2021||11/28/2021|
|Design with Community in Mind||11/22/2021|
|Electric and Magnetic Fields (EMF)||11/22/2021|
|Permitting: Environmental and Regulatory||11/22/2021|
|Comparison of Underground and Overhead Power Lines||11/22/2021|
|400-Scale MCF Project Mapping||10/14/2021|
|Phase 4 - Milvon to West River Fact Sheet||09/04/2020|
|Fairfield to Congress Fact Sheet||07/15/2021|
|Phase 3 - Raymark/Contract Plating Info sheet||05/01/2020|
|Phase 3 - HRX to Baird Fact Sheet||03/17/2021|
|Transcript: Milvon to West River Transmission Open House Video||01/18/2022|
|Transcript: Milvon to West River Transmission Line Upgrade Project Video||01/18/2022|
United Illuminating (UI) is a subsidiary of AVANGRID. Established in 1899, UI is engaged in the purchase, transmission, distribution and sale of electricity and related services to approximately 335,000 residential, commercial and industrial customers in the greater New Haven and Bridgeport areas of Connecticut. UI's service territory includes 17 Connecticut towns and cities in an area totaling 335 square miles along or near the shoreline of Long Island Sound.